Tension controlling means



' Jan. 12, 1937.

H.- 'L. DYER, JR 2,067,755

TENSION C ONTROLLING MEANS Filed July 26, 1933 INVENTOR JZEI'ZerZ' Z.Dyer, rfn

E GQQMM ATTORN EY Patented Jan. 12, 1937 UNITED STATES PATENT OFFICEmermill Paper tion of Pennsylvania ompany, Erie, Pa a corpora-Application July 26, 1933, Serial No. 682,173 8 Claims. (CI. 34-48) Thisinvention relates to the regulation of tension in a web of flexiblematerial such as paper during the travel thereof from one point toanother. In the manufacture of paper the maintenance of proper tensionin the traveling paper web has long presented a troublesome and annoyingproblem. Indeed, were it not for the fact that a web of paper will standconsiderable abuse,

-most of the present paper-making machinery would be useless. The webduring the passage over a paper machine, is constantly changing inlength, becoming longer at some places and shorter at others; and thischange, moreover, is not uniform, since it depends upon various factorswhich are difflcult to maintain constant. As a result, the tension inthe web of paper as it passes through the machine is frequently toogreat or too little. When the tension is too great, the web may break orwrinkle, or it may develop an unbalanced ratio of expanslon or lose someof its tensile strength. When on the other hand, the tension becomes toosmall, the paper is likely to shift back and forth across the. width ofthe machine and to wrinkle; and if this slackness occurs in the webentering the calenders the paper will be cut by the latter. A slacksheet leaving the couch roll will be marked thereby; while if the sheetbecomes unduly slack in the presses it will run up on the ductors andbreak down.

The present invention provides means comparatively simple inconstruction, for effectively controlling the tension in a sheet offlexible material. By this invention provision is made for reliably andautomatically maintaining the desired tension in the sheet or web. Theinvention also enables slack to be readily and emciently taken up. Itfurther provides for maintaining a desired drying effect upon the paperweb despite variations in the drying action of drying cylinders. Otherfeatures of the invention will be hereinafter described and claimed.

In the accompanying drawing: Fig. 1 is a view in perspectiveillustrating an embodiment of the invention applied to a web of papertraveling between two drying cylinders.

Fig. 2 is a diagrammatic view illustrating the action of the embodimentshown in Fig. 1.

Referring to the drawing a sheet or web of paper I is shown passing overdrying rolls or cylinders 2, 2 of well known type. Two parallel carryingropes, customarily employed for threading the paper over the cylinders,are indicated at 3--3. In the space between said cylinders there ispositioned a tiltable frame including two rollers 4, 5 which engage thesheet on opposite sides thereof and which are spaced from eaohother inthe direction of travel of the sheet. These rollers 4, I are rotatablymounteld in the frame members 8. 1, which are pivotally mounted inbearings I, I, respectively. Provided by suitable brackets 5 l0, II. Theaxis about which the members 6, I are tiltable or rotatable is, in theembodiment shown, parallel to the axes of rotation of the rollers 4, 5.

The rollers aforesaid may" be each rotatably 10 mounted on correspondingrods 4', 5, secured at one end in'bosses or extensions l2, l3,respectively, on the framemember 8. At their other ends said rods 4', iare each mounted in a corresponding one of a pair of arms l6, H. Thelatter. as shown, 15

.extend in opposite directions from, and are secured to, a pair of studsl8, l9 fastened to opposite ends of the frame member I. It will thus beseen that the frame comprising the rollers 4, 5, and members 6, I, isreadily tiltable as a unit, and that atthe same time, due to theprovision of the studs l8, l9 and arms I8, I'I, tilting of said framethrough the desired range may take place without interference from thecarrying ropes I, I. Suitably secured to the frame member 1, as by 25being splined or otherwise secured to an extension of the shaft 1',through which the member I is iournaled in the bearing 9, is a cam 20 towhich is fastened one end of a flexible cord 2i, which passes over theperiphery of the cam and carries at its other end the weight 22. It willbe readily apparent that due to the action of said weight a torque isconstantly exerted upon the shaft 1', and that the'frame comprising therollers and members 8, 1 aforesaid is thereby constantly urged in suchdirection as to maintain the rollers 4, 5 firmly pressed againstopposite sides of the sheet or web. Slack in the web between the rolls2, 2 is thus eflectively taken up and the web is continuously maintainedunder tension. 40 If a constant tension be desired in the variouspositions of tilt of the frame aforesaid, the cam may be designed inaccordance with the principles illustrated in Fig. 2. In this view, 0represents the axis about which the frame including the rolls 4, 5, ispivoted, while F is the downward force exerted by the weight 22, andconstantly tending to rotate said frame about axis 0 in acounter-clockwise direction. E0 is the perpen- 60 dicular distance fromthe line of action of the force F to the axis 0. T is the total pull inthe sheet of paper, tending to rotatesaid frame about the axis 0 in aclockwise direction. MO and N0 are the perpendicular distancesfrom O tothe in response to decrease in drying,

lines of actionof 'I. In order to produce equilibrium: I

T(MO and NO) =FXEO Now F is constant, and if T is to be maintainedconstant despite variations in MO and NO (which will change withvariations in the angle a) it will be seen that the periphery of cam 20should be so designed that the distance E0 is directly proportional toM0 and NO. Should, however, a tension varying with changes in theposition of the frame members 6, I and rollers 4, 5, about the axis 0 bedesired, the periphery of cam 20 can be shaped accordingly.

When the tension controlling frame above described is positioned betweendryer cylinders 21, 2, as shown, it not only effectively regulates thetension in the web but furthermore controls the drying thereof. Thetension of the web of paper passing between adjacent dryer cylindersarises from shrinking of the paper due to drying. .Assume, for example,that a slight decrease in the drying action of one of the cylindersoccurs. The tension of the web between the cylinders now tends todecrease, with-consequent lengthening of the web between the cylinders.However, due to the action of the tension controlling frame abovedescribed, the tension is maintained undiminished and the increase inlength of paper is converted into increased wrap of the paper about thecylinder. In other words, upon decreased drying action of a cylinder thetension controlling frame increases the area of contact between thepaper and the cylinder. increasing the drying of the paper by thecylinder. The wrap of the paper around the cylinder is, in short,increased to the point where the increased drying due to increased wrapresults in a tension due to increased shrinkage which balances thetendency for a decrease in tension arising from said decreased drying.Un-

due increase in drying action of a cylinder gives rise to such shrinkingof the paper between adjacent cylinders as to rock the frame aforesaidclockwise against the action of the weight 22, but the area of contactof the paper with the cylinders is now decreased with resultant decreasein drying to the proper point. It will thus be apparent that, due to theprovision of said tension controlling frame the area of contact betweenthe paper and a drying cylinder is automatically increased or decreasedto compensate for decrease or increase of drying action in the cylinder,with resultant maintenance of a substantially constant drying effectupon the paper.

While the invention has been specifically described in conjunction withthe regulation of tension in a web or sheet of paper, it will beapparent that its utility is not confined to paper and that it mayinstead be employed for controlling the tension of, or taking up slackin, webs of flexible material generally. I

- The terms and expressions which I have employed are used as terms ofdescription and not of limitation, and I have no intention, in the useof such terms and expressions, of excluding any equivalents of thefeatures shown and described or' portions thereof, but recognize thatvarious modifications are possible within the scope of the inventionclaimed.

I claim: 1. In combination, a pair ofdrying cylinders adapted to have aweb of flexible material passed thereover and to rotate in oppositedirections during the travel of said material, means responsive tovariation in the drying action of said cyl-' inders for changing thearea of contact between said web and said cylinders to compensate forsaid variation, said means comprising elements spaced from each other inthe direction of travel .5

of said web and engaging opposite sides of the latter between saidcylinders, and means constantly urging said elements to rotate about anaxis spaced from the longitudinal axes of said elements and in suchdirection as to exert'forces 1 against the sides of said web.

2. In combination, a pair of drying cylinders adapted to have a web offlexible material passed thereover and to rotate in opposite directionsduring the travel of said material, means engage- 15 able with said weband responsive to variations in the drying action of said cylinders uponsaid web to cause the latter to bear with constant pressure upon saidcylinders despite variations in said drying action, said meanscomprising elements bearing against opposite sides of said web at pointsbetween said cylinders and means causing said elements to exert pressureagainst opposite sides of said web.

3. In combination, adapted to have a web of flexible material passedthereover and to rotate in opposite directions during the, travel ofsaid material, means engageable with said web and responsive to atendency of the web to vary in length for causing the web to bear withconstant pressure upon said cylinders and over such area as to maintaina constant drying eifect'upon said web, said means comprising elementsbearing against said opposite sides of said web at points between saidcylinders and means causing said elements to exert pressure againstopposite sides of said web.

4. In combination, a pair of drying cylinders adapted to rotate inopposite directions and to have passed thereover a web of flexiblematerial variabie as to length under the drying-action of saidcylinders, means engageable with said web and responsive to a tendencyof the web to change in length for automatically causing said web tobear with such pressure and over such area upon said cylinders as tomaintain the tension in said web constant despite variations in theinternal characteristics of said web under the drying action of saidcylinders, said means comprising elements bearing against said web atpoints between said cylinders and means causing said elements to exertpressure against opposite sides of said web.

5. In combination, a pair of drying cylinders rotatable in oppositedirections adapted to have area upon said cylinders as to maintain acon- 65 stant tension in said web despite variations'in the internalcharacteristics thereof under the drying action of said cylinders.

6. In combination, a pair of drying cylindersv rotatable in oppositedirections adapted to have 7 passed thereover a web of flexible materialvariable in length under the drying action of said cylinders, meansengaging opposite sides of said web between said cylinders andresponsive to a tendency of a pair of drying cylinders 25 said .web toincrease in length between said cylinders for automatically taking upthe slack in said web and maintaining a constant tension therein whileconcurrently increasing the extent of wrap or said web on said cylindersand causing an increased length of said web to be exposed therebetween.

7. In combination, a pair of drying cylinders adapted to have a web offlexible material passed thereover and to rotate in opposite directionsduring travel of said material, and means for taking up the slack in andmaintaining a constant tension in the web of material between saidcylinders, said means comprising elements spaced from' each other andengaging opposite sides or the web between the cylinders, and meansexerting a torque for urging said elements to rotate about an axisspaced from said elements into engagement with said web.

8. A device in accordance with claim 7 in which the urging meanstransmits its torque to the elements by ofiset crank arms whereby anunobstructed passage may be maintained from 10 one cylinder to theother.

HERBERT L. DYER, Ja.

